A DC-DC converter converts a source of direct current (DC) from an input voltage to a desired output voltage and may be provided in various applications, such as those particularly important applications related to the rapidly changing information communications field.
In a DC-DC converter configured as a charge pump converter having a voltage doubler circuit, a supply voltage supplied from a power supply unit of a storage device, such as a battery, etc. may become temporarily unstable due to a high amount of inrush current flowing into the circuit in an initial operation, such as a start-up operation, for example, when powering up a device comprising the voltage doubler circuit. Such an unstable effect may have an undesirable influence on the operation of other adjacent circuits and may be a factor of shortening the life of the battery.
It is therefore preferable to develop an enhanced technology to enable a resistance value to be increased to a greater value when a relatively low switching current is needed in an initial operation and to enable a resistance value to be decreased to a smaller value when a relatively high switching current is needed after the initial operation, without a significant change in components or circuit configuration.